A Case of Road Design in Mountainous Terrain with an Evaluation of Heavy Vehicles Performance

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A Case of Road Design in Mountainous Terrain with an Evaluation of Heavy Vehicles Performance

Barbora Srnová

Master Thesis in Highway Engineering Stockholm, June 2017

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Acknowledgements

This master thesis was carried out at the School of Civil Engineering at the Technical University of Madrid (Universidad Politécnica de Madrid) under supervising of prof. Manuel G. Romana from UPM, Madrid and Romain Balieu from KTH, Stockholm.

I would like to thank the Technical University of Madrid for allowing me to work on this thesis in their labs and their computers throughout the whole duration of the thesis. It was a great experience to spend 5 months at UPM Madrid alongside PhD students who also helped and supported me.

I would also like to thank KTH Stockholm for their support while I was reaching out to UPM Madrid and during my stay there. I appreciate their help throughout this project and throughout my whole master degree studies at KTH Stockholm.

My thanks goes also to Ricardo Lorenzale Grande from UPM Madrid, who patiently helped me with learning how to work with software Tool CLIP and always promptly answered my questions.

Last but not least, I want to emphasize the support that my parents and family have provided me with, I would never be able to chase my dreams and ambition without their continuous help and encouragement for what I am incredibly grateful.

Stockholm, June 2017 Barbora Srnová

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Abstract

Traffic situation in the mountainous surroundings of Navas del Rey, Spain, requires a new solution to improve the road M-501 leading long way around the town. In this project, a solution was suggested and analyzed. A new road was designed to make the path shorter and more convenient for drivers passing the area every day.

The new road was selected from three alternatives and detailed design was presented in this project. The road provides smooth drive through horizontal and vertical alignments with a short section of steep longitudinal grade. This can cause difficulties especially to heavy vehicles, which were thereafter analyzed.

The heavy vehicles performance is affected by several factors, including longitudinal grade, horizontal curve radii and vehicle characteristics. Number of different solutions were presented and described.

Eventually, the most suitable option for the new road was selected. For the section with steep longitudinal grade, 2+1 roadway will be applied to increase capacity of the road. Time period restrains will also be installed to eliminate heavy vehicles from passing the new road during peak hours on working days.

Key words: road design, steep grade, upgrade, downgrade, heavy vehicles, passenger car equivalent, mountainous terrain

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Notation

Abbreviations:

AASHTO American Association of State Highway and Transportation Officials ADT Average Daily Traffic

AV Autonomous Vehicles

EU European Union

EUR Euro, Currency of Eurozone

HCM Highway Capacity Manual

LOS Level of Service

NMAS Nominal Maximum Aggregate Size PCE Passenger Car Equivalent

SEK Swedish crown, Swedish currency

UPM Universidad Politécnica de Madrid (Technical University of Madrid) WTPR Weight-to-Power Ratio, kg/kW

Symbols:

a deceleration rate, m/s² L minimum length of spiral, m

R radius of curve measured to a vehicles’ center of gravity, m Rmin minimum radius of curve, m

s grade of an uphill/downhill, % V design speed, km/h

v vehicle speed, m/s v/c volume-to-capacity ratio y elevation for the parabola, m

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List of Figures

Figure 1: Location of Navas del Rey in Spain ... 3

Figure 2: Location of Navas del Rey in Community of Madrid ... 3

Figure 3: Existing road M-501 in grey color ... 4

Figure 4: ADT on road M-501 ... 4

Figure 5: Alternatives for Section 1 ... 6

Figure 6: Alternatives for Section 3 ... 7

Figure 7: Existing road M-501 in grey color, new road in red color... 8

Figure 8: Sections 1-3 of the new road ... 8

Figure 9: Mass diagram of Section 1 ... 12

Figure 10: Haul of Section 1 ... 13

Figure 15: Example cross-section in tangent. Captured from drawing no. 25 ... 17

Figure 16: Concrete safety barrier (Photo Illustration). Source: smithmidland.com ... 18

Figure 17: Delineator posts (Photo Illustration). Source: globalsources.com ... 19

Figure 18: Pavement structure. Captured from drawing no. 25... 20

Figure 19: Speed-distance curves for a typical heavy truck of 120 kg/kW for deceleration on upgrades. Source: HCM 2000 [5] ... 32

Figure 20: Example of a climbing lane on two-lane highway. Source: AASHTO Green Book 2011 [7] ... 32

Figure 21: Schematic of 2+1 roadway. Source: AASHTO Green Book 2011 [7] ... 33

Figure 22: Passing lanes section on two-lane roads. Source: AASHTO Green Book 2011 [7] ... 33

Figure 23: Illustration of the elevation and longitudinal grade of the entire road... 35

Figure 24: Speed of trucks driving from the reading station 6.9 km to 0.0 km ... 35

Figure 25: Travel time for trucks driving from the reading station 6.9 km to 0.0 km ... 36

Figure 26: Goods transport by mode in EU (2009). Source: European Road Statistics (2011) [1] ... 43

Figure 27: Passenger transport modal split in EU (2009). Source: European Road Statistics (2011) [1] .... 43

Figure 28: Catalogue of pavement structures for heavy vehicle traffic categories T00 to T2. Source: 6.1.- ID [2] ... 44

Figure 29: Speed-distance curves for a heavy truck of 85 kg/kW for deceleration on upgrades. Source: 3.1-IC (1999) ... 47

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List of Tables

Table 1: ADT on road M-501 ... 4

Table 2: Comparison of properties of each alternative in Section 1 ... 6

Table 3: Advantages and disadvantages of alternatives in Section 1 ... 6

Table 4: Comparison of properties of each alternative in Section 3 ... 7

Table 5: Advantages and disadvantages of alternatives in Section 3 ... 7

Table 6: Data on horizontal curves of Section 1 ... 9

Table 9: Data on vertical curves of Section 1 ... 12

Table 12: Heavy traffic categories determined from average number of heavy vehicles per day. Source: 6.1.-IC [2]. ... 19

Table 13: Modulus of compressibility in the second cycle of plate-bearing test. Source: 6.1.-IC [2] ... 20

Table 14: Deflection. Source: 6.1.-IC [2] ... 20

Table 15: Milestones of the project ... 22

Table 16: Common project factors. Source: Highway Project Cost Estimating Methods Used in the Planning Stage of Project Development [12] ... 23

Table 17: Truck hill-climbing speeds as a function of weight-to-power ratios. Source: HCM, 1985 [15] .. 28

Table 18: Passenger car equivalent for trucks and buses on upgrades. Source: HCM (2000) [5] ... 30

Table 19: Passenger car equivalents for estimating the effect on average travel speed of trucks that operate at crawl speeds on long steep downgrade. Source: HCM (2000) [5] ... 31

Table 20: Effect of heavy vehicles on traffic flow in upgrade/donwgrade ... 37

Table 21: Types of bituminous mix according to the type and thickness of a layer. Source: PG-3, Art. 542 [18] ... 44

Table 22: Maximum radius for use of a spiral curve transition. Source: AASHTO Green Book 2011 [7] ... 45

Table 23: Suggested spacing for delineators on horizontal curves. Source: National Transportation Library [9] ... 45

Table 24: Minimum turning radii of design vehicles. Source: AASHTO Green Book 2011 [7] ... 46

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1 Introduction

Road infrastructure is essential part of infrastructure services provided to the society among other technical structures, such as railways, bridges, tunnels, water supply, electric grids, telecommunications, etc. Road transport stands for most of the passenger and goods transport in European Union according to the European Road Statistics [1] from 2011. Goods transport in European Union consists from the road transport of up to 47% (2009), while passenger transport on roads is up to 74% of all transport modes (2009) [1].

Therefore, it has been of great importance to build and improve high-quality road systems in order to accommodate the needs of society. By combination of well-designed traffic system, proper road structure and geometric design, the optimal highway can be built. Improvements in road systems are achieved in various sectors of the road design, such as safer intersections, more durable road pavements, better understanding of vehicles performance, etc.

This project will address two closely related topics: solution of a traffic difficulty in Navas del Rey area in Community of Madrid, Spain, and evaluation of heavy vehicles performance in mountainous terrains. While the first part of the thesis will be focused on design of a new road as a solution of exasperating traffic situation in Navas del Rey, containing geometric design, road structure design, budget and schedule, the second part of the thesis will answer and elaborate on couple questions arising from the design part.

Aim of this project is to solve various issues in traffic engineering by using means of civil engineering knowledge and experiences. The first major issue to be solved is the existent path of road M-501 which leads a long way around the town of Navas del Rey, as will be shown later. This path will be changed into a shorter one making it easier and faster to pass the inconvenient section of the road. However, design of this road will form new questions and issues to be solved, out of which the most important one will be addressed, because one part of the newly designed road will have a 9% grade for more than 1.5 km, and performance of heavy vehicles in such conditions creates significant difficulties in traffic. This behavior will be studied and possible solutions suggested.

Road design in Spain is carried out according to Spanish design guidelines and standards, which are Instrucción de Carreteras and Pliego de Prescripciones Técnicas Generales para obras de carreteras y puentes (PG-3). These set of standards and technical aspects were developed by Ministerio de Formento (Ministry of Public Works) and they are the only standards in Spain that are required to be followed. Sections of Instrucción de carreteras interesting for this project are:

 Norma 3.1.–IC. Trazado de carreteras (Geometric design of roads)

 Norma 5.2.–IC. Drenaje superficial (Surface drainage)

 Norma 6.1.–IC. Secciones de firme (Pavement for new roads) [2]

 Norma 8.1.-IC. Señalización vertical (Vertical signing)

The standard PG-3 provides specifications for road construction – for basic materials and final elements of the road.

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Because these standards are published only in Spanish language, translation to English would take too much time, therefore this project was designed according to American standards AASHTO - A Policy on Geometric Design of Highways and Streets (AASHTO Green Book) and Highway Capacity Manual (HCM). In the United States of America, it is required to follow these standards for a road design. Even though some of the data presented in AASHTO Green Book and HCM differ from data in IC and PG-3 due to slightly different dimensions of vehicles in USA and Europe, most of the guidelines are the same for American and Spanish standards.

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2 Road design

2.1 Introduction

Navas del Rey is a town in the Community of Madrid, located 52 km west from the capital of Spain, Madrid. The town is accessed by the road M-501, adjustment of which will be the object of this project. The town is surrounded by village Robledo de Chavela and towns Chapinería and Colmenar from the north and east. To the south of Navas del Rey is Aldea del Fresno, and in the southwest, there is Pelayos Dam separated from the town by a mountain.

Figure 1: Location of Navas del Rey in Spain

Figure 2: Location of Navas del Rey in Community of Madrid

The existing road M-501 begins at the intersection of M-40 and M-511 in Madrid as four-lane motorway and continues as such for 48 km until it reaches the town of Navas del Rey. At this point, the road is narrowed to two lanes and continues north through the town to pass around the mountain. Eventually it turns to southwest again and crosses the Pelayos Dam to continue further southwest. This path of two-lane road is shown in Figure 3 and is of interest in this project.

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Figure 3: Existing road M-501 in grey color

The section highlighted in grey color in the figure above is 9.4 km long with Average Daily Traffic ADT = 12 893 veh/day, out of which 7.25% is heavy vehicles (2015) [3]. ADT in this section of road M-501 has had an increasing tendency in recent years, as can be seen in Figure 4 and Table 1. Therefore, the importance of improving the traffic and travel conditions in this area is increasing too.

Figure 4: ADT on road M-501

2011 2012 2013 2014 2015

10 900 10 900 10 900 11 930 12 893

Table 1: ADT on road M-501

The main problem to be addressed is the detour that drivers have to take in order to get from Navas del Rey to the Pelayos Dam, the direct distance is approximately 4 km shorter (L = 5.6 km) than the existing path. The aim of this project is to design a new path of the road M-501 in a way that the traveling distance and time will decrease while improving the capacity of the road. Also, traffic safety and comfort will be considered in the design.

9 000 10 000 11 000 12 000 13 000 14 000

2011 2012 2013 2014 2015

ADT (veh/day)

Year

ADT on road M-501

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2.2 Methodology

2.2.1 Software

Road design can be done in number of different software programs developed to make an engineer’s life easier. Some countries and some institutions create their own program that suits the best the conditions and standards of the country. Some of these software are:

AutoCAD Civil 3D (USA), Tool CLIP (Spain), Trimble Quantm (Australia), etc.

Geometric design in this project was done in Spanish software Tool CLIP, a 3D designing program developed for design, evaluation and control of execution and construction of highways and railways. This software was used because the designed road is located in Spain and the input material needed for design was available only for work in CLIP.

The program CLIP provides a designer with infinite number of possibilities and options to carry out a road design. It allows a user to freely create horizontal and vertical alignments, adjusting any variables desired, including design velocity, width of the road, road cross slopes, cut and fill slopes, thickness of road structure, etc. Once the horizontal and vertical alignments are created, they are used by the software to create cross sections of the road. Eventually, the software provides the designer with a 3D dynamic view useful for estimation whether the horizontal and vertical curves are compatible. This is essential for road safety – stopping sight distance and decision sight distance must be sufficient to prevent accidents.

2.2.2 Alternatives

Designing a road is a complicated process requiring evaluation of different alternatives based on their horizontal and vertical alignment, the position within the area, budget, etc. This kind of evaluating is important to make sure that the designed road will be safe, sufficient for the traffic demand, economical and long-lasting. The alternatives can differ in everything from radii of horizontal curves through road structure and material use to intersections.

The path of the road designed in this project is divided into 3 sections as will be explained in detail later in this chapter. However, only two of these sections were evaluated from several different alternatives. Section 2 (see Figure 8) was designed as reconstruction of existing road, therefore its geometric design only followed the road in place. Section 1 and Section 3 were designed as a new road with three alternatives each. These are presented in Figure 5 and Figure 6. The most important factor for evaluation of different alternatives in this project was horizontal and vertical alignment. Economical evaluation was carried out only for the chosen path.

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Figure 5: Alternatives for Section 1

In Figure 5 above, three alternative paths for Section 1 are shown. The paths are similar in vertical alignment with longitudinal slope of 5.5% or 6.0% (See Table 2). However, the horizontal alignment varies because of hills and buildings located in the area. None of the alternatives require a demolition or limitation to existing structures. Advantages and disadvantages of each alternative are listed in Table 3.

1 2 3

Rmin (m) 300 200 200

Rmax (m) 600 500 300 Smax (%) 5.5% 6.0% 5.5%

Table 2: Comparison of properties of each alternative in Section 1

Advantages Disadvantages

1

+ continuous road connection in the east + large horizontal curves radii

+ continuous road connection in the west + lower longitudinal grade

- longest path

2 + larger horizontal curves radii

- intersection in the east - intersection in the west - larger longitudinal grade 3

+ shortest path

+ lower longitudinal grade

- intersection in the east - intersection in the west - smaller horizontal curves radii

Table 3: Advantages and disadvantages of alternatives in Section 1

Compared advantages and disadvantages of each of the alternatives resulted into decision, that alternative 1 (presented in red color) in Section 1 was chosen to be the best option. The main decision factor was the horizontal alignment with continuous connection to roads on both ends of the path ensuring the fluent stream of traffic without stopping at an intersection.

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A path in Section 3 was also chosen from three different alternatives as is shown in Figure 6. Path 1 (red) and path 2 (blue) are very similar in horizontal alignment with small adjustments causing difference between their vertical alignment. In the meantime, the 3^rd alternative (orange) differs from the other two in horizontal alignment, and it also reaches a longitudinal slope of 11%. More properties of each of the alternatives are shown in Table 4.

Figure 6: Alternatives for Section 3

1 2 3

Rmin (m) 100 100 55

Rmax (m) 300 300 600 Smax (%) 9.0% 10.0% 11.0%

Table 4: Comparison of properties of each alternative in Section 3

Advantages and disadvantages of these alternatives are listed in Table 5 below. The most important factor in deciding which alternative would be the best was vertical alignment.

Longitudinal slopes are large in all three paths due to overcoming a mountain which will negatively influence the traffic flow through the section. However, counter-measures can be taken to limit the influence. This will be further discussed later. The alternative with the lowest longitudinal grade was the path 1 (shown in red color), therefore this alternative was chosen to be the best one. An important factor which also contributed to this decision was the continuous transition from the newly designed road to the existing road in the west end of the path.

Advantages Disadvantages

1

+ lowest longitudinal grade + larger horizontal curves radii

+ continuous road connection in the west

- longest path

2 + larger horizontal curves radii - larger longitudinal grade

3

+ shortest path

+ large horizontal curve radius Rmax

- largest longitudinal grade

- connects to an unpaved road in the west - small horizontal curves radii Rmin

Table 5: Advantages and disadvantages of alternatives in Section 3

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The horizontal alignment of the new road was designed in the software Tool CLIP. The initial input material to the program was a map of the area obtained from map and register database at the UPM. The map contained contour lines, existing roads, buildings and water areas. Based on this map, different horizontal alignment alternatives were suggested, out of which one was chosen for detailed design (see 2.2.2). The choice was based on radii of curves and continuity of the horizontal alignment as well as on vertical alignment.

Figure 7: Existing road M-501 in grey color, new road in red color

In the Figure 7 above, the situation of the area can be seen. The existing road M-501 is shown in grey color and the new road is shown in red. The new road will start before the existing road M-501 reaches the roundabout near Navas del Rey and will continue to the southwest to the point, where it will connect to the existing M-501 before it reaches the Pelayos Dam. The new road is 2.5 km shorter than the existing road, resulting in the length of L = 6.9 km. The road is divided into 3 sections based on differing conditions influencing the horizontal and vertical alignment, and material of the foundation. The three different sections can be seen in the Figure 8. All three sections create a continuous road without a need of an intersection. In points where the existing road M-501 connects with Section 1 in the East and Section 3 in the West, intersections will be applied. However, the newly designed road will be the main road and existing M-501 will yield.

Figure 8: Sections 1-3 of the new road

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9 2.2.3.1 Section 1

Section 1 of the new road is the eastern part of the road with reading station 0+000.00 at the east end of the section. This section is located in an area where no other roads occur, therefore the horizontal alignment offered various possibilities for design. Section 1 smoothly passes between two peaks and ends at the point, where it connects to the existing road leading southwards. The horizontal alignment of Section 1 is 2.445 km long and consists of 3 curves of different lengths and radii. The detailed data on the geometric properties of the curves can be seen in Table 6. Design of transition curves is not necessary here, since Ri > 148 m (see Table 6 and Table 22). According to the Table 22, maximum curve radius when a transition curve is necessary is Rmax = 148 m at design velocity V = 50 km/h. A drawing of horizontal alignment and cross sections of Section 1 can be found in Appendix C: Drawings.

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Table 6: Data on horizontal curves of Section 1

2.2.3.2 Section 2

Section 2 is 2.607 km long and the existing road is composed of two parts: short segment of 0.6 km is paved road, while the rest 2.1 km of the section is unpaved local road.

The horizontal alignment of the new road mostly follows the existing unpaved road; however, small adjustments were made near intersections. The Section 2 contains 8 curves, where Rmin

= 200.00 m and Rmax = 500.00 m, as seen in Table 7. Transition curves are not needed in this section either, since the Rmin > 148 m (Table 22). A drawing of horizontal alignment and cross sections of Section 2 can be found in Appendix C: Drawings.

Reading

Station Length (m) Radius (m) 0+181,44

76,51 500,00 0+257,95

0+477,89

167,47 200,00 0+645,36

0+696,74

91,06 200,00 0+787,80

0+970,63

76,80 200,00 1+047,43

1+144,04

173,75 500,00 1+317,79

Reading

Station Length (m) Radius (m) 0+017,39

432,91 300,00 0+450,29

0+653,77

548,23 300,00 1+202,00

1+671,42

630,20 600,00 2+301,61

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10 1+375,16

182,52 400,00 1+557,68

1+615,51

156,22 300,00 1+771,73

2+001,32

212,68 500,00 2+213,99

2.2.3.3 Section 3

The final section of the new road will start where the previous part of existing unpaved road ends. This segment is very important for its large difference in altitude between the start and the end point. Therefore, the horizontal curves are of small radii and in proximity to each other. Section 3 also differs from the other two sections in its cross-section disposition.

Although the first two sections are a two-lane road, Section 3 is designed as a 2+1 road.

2+1 roadway is a concept that has been found to improve operational efficiency and reduce crashes for selected two-lane highways [4]. The concept provides a three-lane cross section by implementing passing lanes in alternating directions throughout the whole section (see Figure 21). Areas with difficult conditions require additional passing lanes in order to improve the capacity and comfort of the road. 2+1 roadway concept was designed in Section 3, because the vertical alignment introduced high grade percentage and therefore deterioration in traffic fluency. This situation influences specifically performance of heavy vehicles, which will be discussed in detail in Chapter 0.

The horizontal alignment of Section 3 is more complicated than of the previous sections due to uneasy terrain. This part is 1.856 km long and contains 7 horizontal curves, some of which create 2 S-curves, where the radius R = 100.00 m. Since R < 148 m (as explained above), transition curves for these horizontal curves are needed to secure fluent transition between a tangent and a curve. Length of transition curves was automatically calculated by software CLIP. In the Table 8 below, geometric properties of horizontal alignment can be found.

A drawing of horizontal alignment and cross sections of Section 3 can be found in Appendix C:

Drawings.

Reading Station Length (m) Radius (m)

Transition Curve Parameter 0+390,95

126,00 300,00

0+516,95 0+631,19

109,92 200,00

0+741,11 0+743,86

42,25 65

0+786,11 0+786,11

62,62 100,00

0+848,73

0+848,73 42,25 65

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11 0+890,98

0+894,94

42,25 65

0+937,19 0+937,19

26,74 100,00

0,963,93 0+963,93

42,25 65

1+006,18 1+190,65

42,25 65

1+232,90 1+232,90

39,16 100,00

1+272,06 1+272,06

42,25 65

1+314,31 1+321,17

42,25 65

1+363,42 1+363,42

34,15 100,00

1+397,56 1+397,56

42,25 65

1+439,81 1+606,70

77,25 300,00

1+683,95

2.2.4 Vertical alignment

The vertical alignment of the new road was designed in the software Tool CLIP. It is important to maintain constant operation and capacity throughout the road section. This is also influenced by vertical alignment: the grade (%) of road, the vertical curves, stopping sight distance, etc. The vertical alignment of the new road was designed to follow the terrain as much as possible in order to lower excavated rock volume as well as to decrease the need for fill material and to reach balance between cut and fill. The terrain where the new road will be located is defined as mountainous terrain: “A combination of horizontal and vertical alignments causing heavy vehicles to operate at crawl speeds for significant distances or at frequent intervals” [5]. In such cases, it is difficult to control cubature - to manipulate the vertical alignment in a way that the excavation material volume is in balance with embankment volume. Important criterion to ensure road safety is to make sure that horizontal and vertical alignments are compatible and that stopping sight distance is reached. This matter was checked for all sections using 3D dynamic view in software CLIP.

2.2.4.1 Section 1

Vertical alignment of Section 1 of the new road was important for horizontal alignment design since this section passes between two hills. The maximum longitudinal grade reached 5.5% throughout almost 600 m of length. The alignment consists of 4 vertical symmetrical parabolic curves of different radii. Length of each curve and elevation for the parabola (y) was

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automatically calculated by the software CLIP. Detailed properties of the vertical alignment are displayed in Table 9. The drawings of longitudinal cross section can be found in Appendix C:

Drawings.

Reading Station Elevation Slope (%) Length (m) Radius (m) y (m)

0+000,000 692,000 0 0 0,000

0+341,250 678,350 -4,0 275 5 000 1,891

0+790,903 685,095 1,5 280 7 000 1,400

1+390,000 718,045 5,5 425 -5 000 -4,516

2+047,500 698,320 -3,0 140 10 000 0,245

2+445,323 691,709 -1,6 0 0 0,000

Table 9: Data on vertical curves of Section 1

Vertical alignment also determines the rock volume needed to excavate or to place. It is important to evaluate balance between cut and fill in order to be able to estimate the time necessary for excavation and financial resources required for excavation and embankment. For this purpose, a mass diagram was carried out. The mass diagram is a graphical representation of the cumulative amount of earthwork moved along the centerline and distances over which the materials are to be transported [6]. Mass diagram from Figure 9 is simplified and shows the change of earthwork volume across the whole Section 1. Positive numbers represent volume of excavated material while the negative numbers show the volume of embankment.

Figure 9: Mass diagram of Section 1

While the mass diagram represents amount of moving material at each cross section, it does not provide clear information on the total volume of excavation or fill. This can be found in a haul diagram. Haul is defined as the transportation of excavated material from its original position to its final location in the work or other disposal area [6]. The haul of Section 1 (Figure 10) contains only positive figures of rock volumes and the haul at the end of the section is

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59 931.6 m³ of excavated material, which means that almost 60 thousand cubic meters of this material will be transported to a storage area. The distance and the direction of transport of the excavated rock was not necessary to calculate for this project.

Figure 10: Haul of Section 1

2.2.4.2 Section 2

Design of vertical alignment for Section 2 was based on achieving balance between cut and fill and reducing large longitudinal grade since the path leads through a valley. It was not possible to make large changes to horizontal alignment because this section is a reconstruction of an existing unpaved road, therefore the adjustments in vertical design were limited to manipulation of horizontal alignment.

The vertical alignment of this section contains 5 vertical symmetrical parabolic curves of radii from 3 000 m to 5 000 m. The steepest part of the section is from 1.687 km to 2.161 km (474 m) with grade smax = 6.5%. The length of each curve and elevation for the parabola (y) were automatically calculated by software CLIP. Detailed geometric properties of vertical alignment for Section 2 are presented in Table 10 below. Drawings of the longitudinal cross section can be found in Appendix C: Drawings.

0+000,000 692,679 0 0 0,000

0+500,694 682,665 -2,0 250 5 000 1,562

0+831,250 692,582 3,0 255 -3 000 -2,709

1+686,810 645,526 -5,5 480 4 000 7,200

2+160,760 576,334 6,5 280 -4 000 -2,450

2+467,010 674,802 -0,5 150 5 000 0,563

2+606,940 678,301 2,5 0 0 0,000

As an effort to minimize the cut and fill to reach balance between excavation and embankment, minor adjustments to horizontal alignment of existing road were made. Through

0 10000 20000 30000 40000 50000 60000 70000

0,0 0,5 1,0 1,5 2,0 2,5

Rock Volume (m3)

Reading Station (km)

Haul

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the design of vertical geometry, it was possible to make a balanced mass diagram and haul.

The Mass Diagram (Figure 11) displays the amount of earthwork needed at each cross section, where positive figures mean that excavation will take place and negative figures show need for embankment.

Figure 11: Mass diagram of Section 2

Data from the mass diagram were further processed to find Haul (Figure 12) for Section 2. The final amount of rock volume after earthwork was performed along the whole section is 1180.0 m³, which means that most of the excavated material will be used for the embankment in a different location of the section and only 1180.0 m³ will not be used and therefore transported to a storage area outside of the construction site.

2.2.4.3 Section 3

The vertical alignment design for Section 3 was the most important factor in selecting the best alternative out of the three proposed alternatives in the beginning of this chapter (see 2.2.2). The new road in this section will overcome a large elevation difference – 160 m of height

-30000 -20000 -10000 0 10000 20000 30000

0,0 0,5 1,0 1,5 2,0 2,5 3,0

Rock Volume (m3)

Haul

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over the length of 1.86 km. The aim of this design was to decrease the longitudinal grade in order to avoid traffic complications, such as decrease in traffic-flow rate and safety. For a road in mountainous terrain and a design speed of 50 km/h, maximum longitudinal grade is 12% [7].

The vertical alignment of Section 3 consists of 2 vertical symmetrical parabolic curves with radius R = 20 000 m. The largest longitudinal grade in this section and in the entire designed road occurs from 0.30 km to 1.55 km (L = 1.25 km) with smax = 9.0 %. The grade of this size and length required special facility adjustments to improve the performance of vehicles and increase the safety on the road. The cross-section of the Section 3 was changed from two- lane road into 2+1 roadway, which will allow overtaking and therefore smoother traffic flow.

This issue was already mentioned in Horizontal alignment, section 2.2.3.3 and will be further explained in Chapter 0. Detailed geometric properties of vertical alignment for Section 3 are presented in Table 11. Drawings of longitudinal cross-section can be found in Appendix C:

Drawings.

0+000,000 678,000 0 0 0,000

0+300,000 657,000 -7,00 400 -20 000 -1,000

1+550,000 544,500 -9,00 100 -20 000 0,063

1+855,566 518,527 -8,50 0 0 0,000

The mountainous terrain in Section 3 was the reason for the design of steep grade along the whole section and it made it very difficult to avoid large excavation and embankment volumes, which are not desired. In fact, the amount of earthwork throughout this section is enormous. The volumes of earthwork at each cross-section are displayed in Figure 13, where positive figures represent the amount of excavations and negative figures show the embankment volumes.

Figure 13: Mass diagram of Section 3 -10000

-5000 0 5000 10000 15000

0,0 0,1 0,1 0,2 0,2 0,3 0,4 0,4 0,5 0,5 0,6 0,7 0,7 0,8 0,8 0,9 1,0 1,0 1,1 1,1 1,2 1,3 1,3 1,4 1,4 1,5 1,6 1,6 1,7 1,7 1,8

Rock Volume (m3)

Section 3 - Mass Diagram

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While the mass diagram above shows only rock volume at each cross-section along the whole section, haul of Section 3 is of bigger interest due to more complex data being provided.

The Haul diagram (Figure 14) represents total earthwork of Section 3 summed up to see, how much rock will not be used in any other location of the section. The final amount of unused rock volume after the all earthwork is finished, is 170 808.0 m³ of excavated material. Since hauls in previous sections were also excavated rock, the material will be transported to a storage area outside of the construction site where it will be reused for other construction projects.

As was mentioned before, the new designed road is located in mountainous terrain with large and long gradient, resulting in complicated vertical alignment design. Even though the grade of Section 1 and Section 2 did not exceed 6.5%, the grade of Section 3 did not reach grade lower than 7.5% for 1.85 km. This situation formed large amounts of earthwork in each of the sections and created a haul from the entire road of 231 919.6 m³of unnecessary excavated material. However, a total of 117 026 m³ of excavated material will be used for construction of embankments. An Excel file called: “Mass Diagram + Hauls.xlsx” providing detailed data of rock volumes can be found on attached CD-drive.

Note: Small inaccuracies may occur in elevation of land and pavement as a result of separate design for each section.

2.2.5 Cross Section

Cross-section is a vertical section of the ground and roadway at right angles to the centerline of the roadway, including all elements of a highway or street from right-of-way line to right-of-way line [5]. Cross-sections are an essential part of design, as they illustrate the road structure, cross-slope, drainage features, inclination of road-side slopes, elevation of pavement, etc. It is a custom that analyzed cross-sections are spaced 20 or 25 m apart over the whole length of designed road. In Spain, the distance of 20 m is a common practice, therefore there are 40 drawings of 348 cross-sections in Appendix C: Drawings. These cross-sections were

0 20000 40000 60000 80000 100000 120000 140000 160000 180000

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0

Rock Volume (m3)

Haul

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not shown in longitudinal cross-sections as it was not necessary for this project, however, each cross-section in the drawings is assigned with a corresponding reading station.

The road was designed as two-lane road, because it is more efficient and economical in mountainous terrain than a four-lane road. The capacity of the facility will be sufficient for the traffic flow as the existing road around Navas del Rey is also a two-lane road. The design of the road does not consider presence of pedestrians on the road, since the road will connect two towns 6.8 km apart. Bicycles may occur on the road, however, a bike lane was not designed due to the mountainous terrain; the designed hard shoulders on both sides of the road will provide enough space for cyclist to move safely. Total width of the new road is broad = 10.0 m consisting of two traffic lanes of blane = 3.5 m and external hard shoulders on both sides of the road, bshoulder = 1.5 m. Hard shoulders serve as a lane available for emergency stops and provide extra space during reconstruction and maintenance of the road. The cross slope of traffic lanes and hard shoulders is identical at the tangents with a crown in the middle and a cross slope of s = 2.0% downward towards the edges (Figure 15). The same cross-slope was designed for the road structure, which means it has the same cross-slope as the traffic lanes at any cross-section along the road.

Figure 15: Example cross-section in tangent. Captured from drawing no. 25

When a vehicle moves in a circular path, it undergoes a centripetal acceleration that draws the vehicle toward the center of the curvature [7]. This acceleration is reduced by superelevation of the road, which creates a side friction between the pavement surface and the vehicles’ tires. The maximum rate of superelevation depends on local climate, road constructability, frequency of slow-moving vehicles, etc., however the highest superelevation slope in common use is 10.0%, in areas with possible snow and ice only 8.0% [7]. The maximum cross-slope used in this project was s = 7.6% at curves of R = 100 m in Section 3. The superelevation for the entire project was calculated automatically by software CLIP.

Highway drainage design ensures road safety, control of pollutants and economical maintenance as it removes the stormwater from the road and leads it into culverts and channels to deliver the water into a suitable place, where it will no longer pose a danger to the stability and safety of the road. For this project, side gutters were used as drainage system.

Side gutters are triangular gutters adjoining the shoulder, with purpose of preventing runoff from the cut slopes on the high side from flowing across the roadbeds [8]. Dimensions of gutter

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standardly used in the USA following the Highway Design Manual may differ from the dimensions used in Spain. The side gutter used in this project is a standard gutter with dimensions: depth to the deepest point h = 0.15 m and width bgutter = 1.0 m. The gutter is located at every cross-section which is constructed in cut, so the stormwater runs off the road and does not stay by the road construction body which could cause undesired settlement of the structure.

Sideslopes should be designed to enhance roadway stability and to provide a reasonable opportunity for recovery for an out-of-control vehicle [7]. Foreslopes should not be steeper than 1V:4H unless the road is located in an area that does not permit use of flatter slopes. The backslopes should be 1V:3H or flatter, depending on the area requirements, space availability, financial expenses and, most importantly, on stability of the slope. Because of the design in a mountainous terrain, the foreslopes used in this project are 1V:3H, backslopes in cut 1V:2H. In case of slope’s height H > 3.0 m, a backslope of 1V:1H were used. Backslopes in fill were designed as 1V:2H, in case of height of slope H > 3.0 m, the slope of 1V:1.5H was preferable. These sideslopes are acceptable in the area of Communidad de Madrid, where the geological conditions are very convenient and suitable for construction in steeper slopes.

A roadside barrier is a longitudinal system used to shield motorists from obstacles or slopes located along either side of a roadway [7]. In determining which type of a safety barriers is the most appropriate, the height and slope of an embankment are the most important factors. Rounding at the shoulder and at the toe of embankment slope can reduce the severity of an accident and help the driver to keep vehicle control. The longitudinal safety barrier for this project was designed only on the side of the fill in order to prevent vehicles from riding off the road in sections with high embankment (see Figure 15). The barrier is placed on the outer edge of the shoulder to leave the most area of the hard shoulder free for emergency stoppings and other necessary operations. On the cut side of the road, the foreslope is flat enough to keep vehicles from serious crushes and therefore no safety barrier is necessary.

The roadside barrier used in this project is New Jersey wall (Figure 16) – a type of concrete safety barrier New that can provide strong support not only for passenger cars, but also for heavy vehicles.

Markings of the road systems provide road users with regulations, guidance or warning, which is reason why markings are essential elements of driver communication.

Horizontal markings and vertical signs of the new road were not designed in this project as it was not necessary for the purpose of the project. However, a requirement for all rural roads is to install delineator posts to increase night visibility and visibility in rain and snow, when most

Figure 16: Concrete safety barrier (Photo Illustration). Source:

smithmidland.com

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of the horizontal markings are covered and not visible. The purpose of delineator post is to outline the edges of the roadway and to accent critical locations. Delineators consist of retroreflective devices which are able to reflect a vehicle light from a distance of 300 m. The delineators in this project will be mounted with posts 1.35 m above the pavement on the cut side of the road, and installed without a post on the concrete safety barrier, since the retroreflective elements should be along the both sides of the road. The height of delineator posts on concrete barriers is 0.45 m to ensure good visibility of reflection. In the tangent sections, the delineators will be spaced 150 m apart in a continuous line, placed 0.5 m outside the hard shoulder [9]. The spacing of delineator posts in a

curve depends on radius of the curve, but should not be less than 6 m and more than 90 m.

The values for the spacing in curve can be seen in Table 23. The posts of delineators can be made from various materials, such as: U-channel iron post, standard black pipe, plastic or timber post. In this project, plastic delineator posts will be used, and because they are fragile, they do not pose any risk for road safety.

2.2.6 Road structure and materials

Primary function of a road structure is to distribute applied vehicle loads to the subgrade and reduce them so they will not exceed bearing capacity of the sub-grade. Pavement structure should provide a surface of desired quality, adequate skid resistance, favorable color and light reflection and low noise pollution. A properly designed pavement ensures its longevity, riding comfort and low maintenance cost.

Design of a road depends on the type of the road, average daily traffic, average daily heavy vehicle traffic and geology of the subgrade. These factors decide whether the pavement will be flexible or rigid, what thickness and material composition of the structure will be. These design questions are answered in Spanish standard Norma 6.1.-IC dealing with pavement for new roads.

Heavy traffic category of the road was determined from Table 12, where IMDp stands for Average Daily Heavy Traffic and is expressed in heavy vehicles per day. As mentioned in 2.1, the ADT on M-501 is 12 893 vehicle/day with 7.25% of heavy vehicles, which equals to 935 heavy vehicles per day. Therefore, the heavy traffic category is T1.

Table 12: Heavy traffic categories determined from average number of heavy vehicles per day. Source: 6.1.-IC [2].

Category of the subgrade (Categoria de explanada) is determined based on modulus of compressibility from the second cycle of plate-bearing test performed according to the NLT-

Figure 17: Delineator posts (Photo Illustration). Source: globalsources.com

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357: Ensayo de carga con placa. The categories are E1, E2 and E3 (see Table 13). In this project, the test was not performed neither the value calculated, therefore, the subgrade category E2 was assumed. For E2, the modulus of compressibility Ev2 = 120 MPa.

Table 13: Modulus of compressibility in the second cycle of plate-bearing test. Source: 6.1.-IC [2]

For the purpose of control of the subgrade execution and for the categories of heavy traffic T00-T2, the maximum standard deflection is allowed in accordance with Table 14. The shown values, however, are probable values of the support capacity of the subgrade, varying due to changes in humidity. For the subgrade category E2, the maximum allowed deflection is dmax = 200*10^-2mm.

Table 14: Deflection. Source: 6.1.-IC [2]

Based on heavy traffic category (T1) and subgrade category (E2), the thickness of the pavement structure was designed according to the Figure 28. Structure number 122 was selected consisting of 20 cm of hot bituminous mix (MB) as surface course and 25 cm of stabilized cement (SC) as subbase. The subgrade of the pavement structure is 30 cm of stabilized cement. The layers and the materials of the surface course were designed following the Table 21. The pavement is displayed in Figure 18 and it is also included in the Appendix C:

Drawings, drawing No. 25.

Figure 18: Pavement structure. Captured from drawing no. 25

The function of surface course is to provide resistance against wear due to traffic loads, to provide smooth riding surface for more comfort, to resist the vehicle pressure and surface water infiltration. It also prevents horizontal shear stresses and vertical pressure produced by moving or standing vehicle load and distributes the wheel load pressure [10]. The thickness of the surface course is 20 cm and consists of the following layers:

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 Semi-dense surface asphalt concrete with nominal maximum aggregate size of 16 mm, bitumen penetration index B40/50 and thickness t = 4 cm (AC 16 surf S B40/50)

 Semi-dense binder asphalt concrete with NMAS of 32 mm, B40/50, t = 6 cm (AC 32 bin S B40/50)

 Coarse base asphalt concrete with NMAS of 32 mm, B40/50, t = 10 cm (AC 32 base G B40/50)

The subbase course acts as support for surface course, it improves drainage condition and protects upper layers from undesired qualities from underlying soils. The material used for the subbase course is stabilized cement (SC) with thickness t = 25 cm.

Underneath the subbase course, subgrade layer is constructed, which receives the distributed traffic load from the layers above, withstands all types of stresses imposed upon it and acts as bedding layer for the whole structure.

2.2.7 Schedule

A schedule of construction project is important part of project documentation carried out in order to establish production goals, to monitor and measure progress and to manage changes to the project along the way. Time management of a project is essential to the entire production, as it prevents and eventually solves issues of time delay or time conflict between different activities.

Bar chart is the most commonly used method of planning and scheduling construction projects [11]. Bar charts are easy to prepare, easily understood and they are oftentimes referred to as Gantt charts. However, they do not show the relationships between activities and what effect a time delay of one activity could have on the timeline of the rest of the project.

The position and length of each bar in the Gantt chart reflects how long each activity is scheduled to last, when it starts and ends, what activities overlap and eventually, when the entire project starts and ends. The excel file with schedule of this project can be found on attached CD-drive as “Schedule.xlsx”.

Every construction project should have milestones which are important to reach during the construction, because they provide easier check of completed project stages and time delays. For this project, 13 milestones and expected time of their accomplishment have been set:

Milestone Week

ML1 Access to all sites for surveying and geotechnical reconnaissance equipment to contractor 1

ML2 Approval of quality of surveying by client 4

ML3 Approval of quality and reliability of geotechnical knowledge by client 5

ML4 Approval of quality of Section 1 by client 11

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ML7 Approval of safety and adequacy of temporary facilities designed by client 19

ML8 Submittal of Draft Detailed Design to Client 20

ML9 Result of Review of Draft Detailed Design by Engineer 22

ML10 Result of Review of Draft Detailed Design by Client 23

ML11 Result of Review of Final Detailed Design by Engineer 28

ML12 Result of Review of Final Detailed Design by Client 31

ML13 Submittal of Final Detailed Design to Client 32

Table 15: Milestones of the project

The schedule of the construction project was divided into 9 groups of activities (A-I):

(A) Previous work, (B) Pre-construction activities, (C) Construction site preparation, (D) Section 1, (E) Section 2, (F) Section 3, (G) Translation and checking, (H) Final edition and submittal (Draft Detailed) and (I) Final edition and submittal (Final Design). Each of these groups lasts from 5 weeks to 18 weeks, resulting in the scheduled length of the entire project to be 32 weeks (8 months).

Section 1 and Section 3 will start one week apart, Section 1 will start from the beginning of the reading station, Section 3 from the end of the reading station and the construction will continue towards the middle of the new road. This way, the works will be in progress in two places at once, and the project completion time will be approximately 10 weeks shorter (the time of construction of Section 3). Construction of Section 2 will start once Section 1 is finished, and since it is scheduled that Section 2 activities finish after Section 3 is ready, the work of these two parts will meet towards the end of reading station of Section 2.

The final 32 weeks of construction project consist of 17 weeks of construction work and 15 weeks of administration work including planning, surveying, geotechnical study, revisions and reviews, legislation check and final submittal.

2.2.8 Cost estimation

A road project like this one requires a cost estimation of the construction process. Cost estimation is the process by which, based on information available at a particular phase of project development, the ultimate cost of a project is estimated [12]. It is also the first estimate used for evaluating budget and allocation of resources. Cost estimation is a part of the initial project documentation that can help a project manager to make better decisions regarding the limitations of the project.

A construction project is described by many factors, such as terrain, number of lanes, rural or urban setting. Table 16 contains a list of factors typically used for estimation cost during planning stage of the project. Most of these factors are considered in the cost estimation carried out in this project. The cost estimation is provided in Appendix B: Cost Estimation. The costs are divided into chapters in the attached cost estimation and these are: excavation, transverse drainage, longitudinal drainage, pavement, signalization, environmental integration, various, contingencies, safety and health at work, unknown and taxes.

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Cost of excavation accounts for excavation of top soil (t = 0.2 m) and mechanic excavation of all the required soil as well as embankment works, including transport of the material within the construction site or to a quarry. The amount of excavated material was calculated from mass diagrams presented in 2.2.4.

Table 16: Common project factors. Source: Highway Project Cost Estimating Methods Used in the Planning Stage of Project Development [12]

Transverse drainage in this project are culverts for draining water away from the road structure. The culverts are located every 50 m of the road and in the lowest points of the vertical alignment to avoid standing water in sag. The number of culverts was assumed based on this standard, but due to time restraints of the design work, they are not presented in horizontal or vertical alignment drawings.

Longitudinal drainage will be installed on the cut sides of the road so the stormwater from the road and slopes does not stay by the road but flows away and to a culvert. If the water is not lead away from the road, it would significantly affect the material properties of the road structure. Three types of longitudinal drainage are used: a side ditch covered with concrete suitable for sections with longitudinal grade less than 1% or more than 3%; prefabricated ditch appropriate for road sections where the sideslope exceeds height of 5.0 m; and concrete ditch installed on the cut sides of the road where the two previous drainage types do not apply.

The cost of pavement was calculated separately for each material used considering the thickness of a layer, width and length of the entire road. The pavement structure was explained earlier in section 2.2.6. For the cost estimation, also 30 cm layer of subgrade was counted in as a quality base for the road structure.

The price of horizontal and vertical signalization is estimated per kilometer of road and represents only assumption of amount of used signalization. The exact number of vertical signs or volume of horizontal signs was not calculated in this project.

Important part of every road project is environmental integration evaluating the impact that the construction of the road has on the environment. Maintenance of the road slopes to minimize the negative impact is a common practice to prolong the life of the entire road structure. The cost estimation of environmental integration in this project includes:

unpacking of the land; maintenance, transport and spread of top soil from the excavation;

hydroseeding and maintenance of plant species. These values were assumed.

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From the chapter Various, the only process performed in this project is removing of existing way in the Section 2. The length of the existing road is 600 m and it will be replaced with a new road to match other sections of the road.

Cost estimates not always include contingencies – money added to the final cost estimate as a precaution for unforeseen situations, such as weather delays or changes in scope [12]. Depending on the size and difficulty of the project, contingencies add to a cost between 5% and 15%. For this project, 10% of the final cost was assumed.

Safety and health at work includes cost for introducing safety programs at the construction site and for possible work-related injuries and illness. It is of utmost priority to create a safe and healthy environment on the job site, therefore the cost of such precautions is included in the initial estimation cost. For this project, 2% of final cost was assumed.

The cost estimation Chapter 10: Unknown assumes cost of some items not included in the previous chapters due to the size of this project and the time constraints for submittal.

Items not included were, for instance: concrete barriers, delineator posts, management overhead, etc. For these items, 15% of the final cost was assumed.

After all the chapters and items were put into cost estimation of the project and summed up, the estimated cost was approximately 5.66 mil €. However, taxes apply for a project cost. In Spain, the taxes for construction projects are 21%, which puts additional 1.19 mil € to the project cost resulting in the total estimated cost of 6.85 mil €.

The most costly item on the cost estimation list is hot bituminous mix with asphalt binder resulting in up to 30% of the cost. The second most expensive item is excavation which creates up to 24% of the cost. Such large number of resources will be used on earthwork because the road is located in a mountainous terrain. The prices used in this project are standard prices generally used in Madrid area, Spain in 2016.

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2.3 Results and Discussion

The goal of the project was to design a new road in order to improve traffic situation in town Navas del Rey, Spain. The existing road M-501 leads a long way around Navas del Rey to the Pelayos Dam because of the mountainous terrain surrounding the local towns.

Therefore, search for solution lead towards the project design of a new road that would shorten the way between Navas del Rey and Pelayos Dam.

Initially, three alternatives of the road were designed with varying length and horizontal and vertical alignment. After weighing advantages against disadvantages of each alternative, the most suitable alternative was chosen and designed in detail. The length of the entire new road passing through the mountainous terrain is 6.9 km, which is 2.5 km shorter than the existing road M-501.

The vertical alignment significantly differs between the sections of the road – while the maximum longitudinal grade in either of Section 1 or Section 2 is 6.5 %, it does not reach lower value than 7.0 % at Section 3. This size of the longitudinal grade is allowed on rural mountainous roads, however, it is inconvenient for mixed traffic including heavy vehicles. For this reason, 2+1 roadway was designed in the Section 3.

The pavement structure was determined based on heavy vehicle traffic and environment of the road surroundings. The thickness of the structure is 45 cm containing three layers of different types of asphalt concrete (bituminous mix) at the surface, and different types of stabilized cement as subbase and subgrade.

The schedule of the project in construction was assumed to be 32 weeks, accounting for pre-work activities (planning, surveying), construction works (excavation, embankment, pavement) and review and submittal activities. However, cost estimation was accounting only for the construction works, such as excavation, embankment, pavement, drainage, environment maintenance, etc. The estimated cost of the project is 6.85 mil €, tax included.

In this project, design of the new road will provide shorter path than the existing road, through which the traffic situation around Navas del Rey will improve. However, this can be said with certainty only for passenger cars and light vehicles, because heavy vehicles can experience problems with steep longitudinal grade in Section 3. This issue will be further discussed and solution suggested in the next chapter: Heavy vehicles performance.

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3 Heavy vehicles performance

3.1 Introduction

Road system is essential mean of passenger transport in Europe creating up to 74% (2009) of all modes of transport (Figure 27). Goods transport also depends on a road transport, since nearly 47% of all goods transport in Europe uses road system (Figure 26). This being said, heavy vehicles play an important role in transport of goods and passengers, as trucks and buses can carry heavy loads of cargo and large number of people.

Since heavy vehicles operate in the same traffic flow as passenger cars, bicycles and pedestrians, it is necessary that the road design counts on all aspects of different behaviors.

Trucks and buses negatively influence the traffic operations and, possibly, capacity of facilities due to their lower performance. The heavy weight being transported applies large load on the road structure which deteriorates over time. However, heavy vehicles are necessary for well- being of the society, hence new solutions must be developed in order to limit the negative effect of heavy vehicles on the road structure and traffic flow.

The road M-501, which is of interest in this project, is a regional road connecting towns across west part of Madrid region. The average daily traffic is ADT = 12 893 veh/day, out of which 7.25% are heavy vehicles (see 2.1). Therefore, it is important to take heavy vehicles into account in the design of the new road and consider their performance in all possible situations to improve overall efficiency of the traffic operations.

3.1.1 Aim and objectives

In Chapter 2, design of new road M-501 was presented with detailed drawings and explanation of used procedures. The new road was separated into three sections for easier handling of varying data and properties of the landscape area. While Section 1 and Section 2 did not pose any issue in design, Section 3 formed a problem with its vertical alignment. Due to a large elevation difference between the start and the end point of the section (160 m on length of 1.86 km), the minimum value of longitudinal grade is smin = 7.0%, while the maximum value is smax = 9.0% over 1.2 km of length. A longitudinal grade of this size causes decline of traffic fluency and safety, therefore the aim of this chapter will be to find solution for improvement of heavy vehicles performance in steep uphill/downhill and to reduce their negative influence on traffic.

A Case of Road Design in Mountainous Terrain with an Evaluation of Heavy Vehicles Performance